EVIDENCES OF EVOLUTION Fossil Record Biochemical Comparative Anatomy Biogeography Observable Events Artificial Selection

Genetic change in a population through time. EVOLUTION IS Genetic change in a population through time. Population Dynamics POPULATIONS IN ECOSYSTEMS

Charles Darwin On his journey around the world, Darwin found evidence of gradual change (evolution). Darwin cited evidences he found in fossil records, geographic distribution and homologous structures.

Evidences of Evolution Today most evidences for evolution are grouped into five main categories: Biochemical Fossil Record Comparative Anatomy Biogeography Observable Events Artificial selection

1 - FOSSIL RECORD Paleontology – study of fossils Fossil – remains or traces of an organism that lived long ago Remains: ex. bone, tooth, or shell Traces: ex. burrow, footprint, or imprint Photos by cbray

1 - FOSSIL RECORD Most fossils are found in layered sedimentary rock Oldest fossils are in the deeper layers Life on Earth has changed Increased number of life forms Layers diagram by cbray

Fossil Record The fossil record is the history of life recorded by remains from the past. Most fossils are at least 10,000 years old. Body Fossils Trace Fossils

2 - BIOCHEMICAL THE GENETIC CODE Triplets of DNA nitrogen-base sequences that code for specific amino acids The sequences of bases that code for amino acids are the same in almost all organisms. Genetic code table by cbray

2 - BIOCHEMICAL The similarity of triplet DNA codes making-up amino acids shows: A probable common ancestor for all life on Earth

2 - BIOCHEMICAL “Universal” GENETIC CODE Similar genes Over the ages, the genetic code has passed unchanged (or nearly so) from parent to offspring.

Number of differences from human hemoglobin 2 - BIOCHEMICAL AMINO ACID SEQUENCING The amino acid sequence in a particular protein is compared between organisms. 8 125 45 27 Amino acid differences designed by cbray (with PPT clip art) 67 1 Number of differences from human hemoglobin

Amino Acid Difference in Hemoglobin Compared with Human 2 - BIOCHEMICAL Comparing amino acid sequence shows: Closeness of relationship A probable common ancestor Amino Acid Sequencing is probably the STRONGEST evidence for relationships among organisms. Amino Acid Difference in Hemoglobin Compared with Human Species Difference Gorilla 1 Rhesus Monkey 8 Mouse 27 Chicken 45 Frog 67 Lamprey 125 Amino acid differences chart by lpriddy Human hemoglobin has 146 amino acids

Number of Amino Acid Differences Amino Acid Difference in Hemoglobin Compared with Human 2 - BIOCHEMICAL Species Difference Gorilla 1 Monkey 8 Mouse 27 Chicken 45 Frog 67 Lamprey 125 CLADOGRAM: diagram that shows the evolutionary relationship among a group of organisms. B A C D Number of Amino Acid Differences 150 100 50 40 20 30 10 Where would the common ancestor be? What organism belongs at each branch? E F Amino acid differences chart by lpriddy G Common ancestor

3 - COMPARATIVE ANATOMY HOMOLOGOUS STRUCTURES structures with different mature forms but develop from the same embryonic tissue ex: limbs of vertebrates (turtle, alligator, bird, mammal) Turtle Alligator Bird Mammal

3 - COMPARATIVE ANATOMY Homologous structures show Similar genes Descent from a common ancestor Turtle Alligator Bird Mammal Ancient lobe-finned fish

Homology Homology: a similarity between species that is the result from the inheritance of traits from a common ancestor The features of every creature reflect history as well as adaptation 3 types of homologies - structural - developmental - genetic

Homology vs. Analogy Natural selection appears to have favored similar adaptations in unrelated organisms in similar environments--> these structures are analogous Whereas homologous structures share structural similarity, but not function, analogous structures share function but not structural similarity since they evolved independently

Genetic Homologies All living organisms share the same genetic code Chromosome and gene similarities between species match evolutionary similarities This is true for both coding regions and “junk DNA”

3 COMPARATIVE ANATOMY VESTIGIAL STRUCTURES organs so reduced in size that they are nonfunctioning remnants of similar organs in other species ex: human tailbone, appendix, whale pelvis an organism’s evolutionary past a common ancestor with species that have similar structures that are still functioning Whale pelvis diagram by cbray

Vestigial Structures in Humans Tailbone Wisdom Teeth Appendix

3 COMPARATIVE ANATOMY EMBRYOLOGY Embryos of different species may appear similar in early stages of development Embryo drawings by cbray ex: vertebrate development

3 COMPARATIVE ANATOMY Comparison of similarities in embryos can show: Relationship to a common ancestor Embryo drawings by cbray

4 - BIOGEOGRAPHY GEOGRAPHIC DISTRIBUTION OF ORGANISMS organisms living widely apart (even different continents) may be similar because they share a common ancestor Beaver Muskrat Beaver and Muskrat Coypu Capybara Coypu and Capybara Shows common ancestor

5 - OBSERVABLE EVENTS Some changes in species have been observed and studied Observable events show that evolution is an ongoing process Peter & Rosemary Grant’s Study of Beak Size Shift in Darwin’s Finches H. Kettlewell’s Study of Peppered Moth Color Shifts

6. Artificial Selection Process by which plants and animals used by humans in agriculture, horticulture, and companionship have been derived from wild organisms Humans use the best or more useful traits provided by nature and pass on to future generations

6. Artificial Selection http://www.gly.uga.edu/railsback/1122/1122Dogs.jpeg

6. Artificial Selection Picture depicting how farmers have cultivated wild mustard and selected the desirable traits Nature provides the variations and humans select those variations that they find most useful

Works Cited “Geographic Distribution of Organisms” photo: Miller, Kenneth and Levine, Joseph. (2004). Biology. Prentice Hall. McGraw-Hill http://pages.uindy.edu/~sdavis/b280/lectures/3evidence1280.ppt.